Punch element and method of making same



July 29, 1952 J; F. KOPCZYNSK] 2,604,742

PUNCH ELEMENT AND METHOD OF MAKING SAME Filed April 11. 1947 2SHEETSSHEET 1 LAW Offering 5'.

y 29, 1952 J. F. KOPCZYNSKI 2,604,742

PUNCH ELEMENT AND METHOD OF MAKING SAME Filed April 11, 1947 2SHEETSSHEET 2 22 FIG. 5

24 20 FIG. 4

, xv M 28 9 FIG. 6

' IN VEN TOR.

Patented July 29, 1952 John-F. Kansas, meat; N. Y. application April"11, 1947, sesame. 740.911

This invention relates to tools, andparticular-ly to punches forpunching holes or ape-rture's sheets.

In punching apparatus the punch element commonly has a reduced endportion or stem which does the punching, and an intermediate or Junetionpart connecting the main body-portion with the reduced end portion orpiercing end. This intermediate part usually is tapered or increasesprogressively in cross sectional area through a plurality of stages fromthe reduced end to the body portion.

It is highly desirable that the ground grain on the sides of the punchelement extend lengthwise in order to provide a clean, punched apertureand lon life for the punch element.

An object of the invention is to'provide an improved punch element witha ground surface on the side of the punching or piercing end, in whichthe ground grain runs generally parallel to the longitudinal axis of thepiercing end; with which the picking up of small particles of stock bythe reduced punch element end will be reduced to a minimum; with whichthe tendency of the punch element to crack and break in use will be'reduced; with which a more perfect blending be tween the reduced endand tapered portion may be obtained; with which heating of the punchduring grinding is reduced; and which will be relatively simple,practical, inexpensive, and of long life. 7

Another object is to provide an improved and simple method ofgrindingthe sides of a punch element to reduce it accurately to thedesired size,

and to form thereon a ground grain running parallel to the longitudinalaxis of the punching end of the punch element; and with which one mayobtain a more perfect blending or merging of the punching end into thetapered section connecting the punching end to the body of the punchelement.

Other objects and advantages will be apparent from the followingdescription of one example of the invention, and the novel features willbe particularly pointed out hereinafter in connection with the appendedclaims.

This invention is a continuation, iln part, of copending applicationSerial No. "673,713 filed May 31, 1946.

In the accompanying drawing:

Fig. 1 is a side elevation of an apparatus constructed in accordancewith this invention-for grinding the sides of the piercing endsbf.punches in a manner to have the ground graineiitending generallylengthwise of the punch j I col-aims. (o1. 51- 2s9) Fig. 2 is a plan ofthe Same;

Fig. 3 is a diagram illustrating, on an enlarged scale, the principleinvolved in grinding the punch element; V

Fig. 4 is an end elevation of the apparatus shown in Figs. 1 and 2;

' Fig. 5 is a sectional elevation of apart of the same, the sectionbeing taken approximately along the line 5-5 of Fig. 1; and

Fig. 6 is a sectional elevation of another part of the same, the sectionbeing taken approximate ly along the line 66 of Fig. 4. v

In the illustrated embodiment of the invention and referring first toFig. 3, the punch element I is provided with a body part 2 bywhich itmay be anchored in a movable member for a punching operation, and at theopposite end is a piercing shank or end 3 or reduced cross-sectionalarea, and with its side surface a surface of revolution such as acylindrical shape. Between these two portions 2 and 3 is an intermediatepart 4 "which is frusto-conical or tapered, with its larger base merginginto the body part 2, and its smaller or convergent end merging into thecylindrical, piercing end 3. The small end of the tapered part '4 mergesinto the piercing end 3 through a concave, arcuate surface 5 having asmall radius of curvature in transverse cross section. The periphery ofthe grinding or abrasive wheel is shown diagrammatically by the circle 6in Fig. 3, and the wheel is rotated about an axis 1 such as in aclockwise direction in Fig. 3.

While the grinding wheel 6 is rotated about axis I in this manner, it isbrought from the position A in Fig. 3 into contact with the side of thepiercing end 3 of the punch element, while the punch element is beingrotated about the longitudinal axis of the piercing end 3. The punchelement is rotated about this longitudinal axis, shown by the dot anddash line E-E in Fig. 3, and while so rotating at a selected speed, thegrinding wheel 6 is moved slowly along and in contact with the side ofthe piercing end 3 in a direction parallel to axis E-E, such as alongthe line"G--G, through the position B to the position C; whichdetermines the length of the piercing end.

The-grinding wheel ii rotates at a substantially greater speed than thespeed of rotation of the punch element. There should be a very substantial excess of speed "of the grinding wheel 6 over that of thepunching element I, in order that the ground grain will run lengthwiseof the piercingend 3. For example, excellent results have been obtainedwhen the punch element I rotates at about 145 R. P. M. and when at thesame time the grinding wheel 6 rotates about its axis 1 at about 55,000R. P. M. Unless the speed of rotation of the wheel 6 is verysubstantially greater than the speed of rotation of the punch element,the best results will not .be obtained, and the speed of rotation of thegrinding wheel should preferably be above at least ten times the speedof rotation of the punch element.

The movement of the grinding wheel 6 along the side of the punch elementI should be relatively slow, so that the piercing end 3 of the punchelement may be brought to the desired size, and when the wheel 6 reachesthe C position in Fig. 3, its movement endwise of the punch element isstopped momentarily and then given a movement along the line F-F,instead of further along the line GG which it followed when grinding theside of the punch end 3. Thus from the C position the grinding wheel 8moves with its axis along the line F-F past the position D until itleaves the punch element beyond the large end of the tapered part 4.

One mechanism for performing such a grinding operation, and which hasbeen found to be very satisfactory, is illustrated schematically inFigs. 1, 2, 4, 5 and 6. Referring now to Figs. 1, 2 and 4 the grinderincludes a base 8 having an upright standard 9. A moving table In ismounted on the upper end of the post or upright standard 9 and itcarries a head stock H which may be shifted endwise on the table throughmanipulation of a screw mechanism operated by a hand wheel l2. Table Iis moved endwise on standard 9 byrotation of wheel Illa. Wheel Illaoperates a pinion (not shown) that drives a rack on the bottom of tableH]. The head stock ll carries spaced bearings [3 which rotatably mount aspindle I4, and the latter has fixed thereon between the bearings l3, adriving pulley I around which passes a belt I0 that, in turn, is drivenby a motor (not shown) or other source of power. The belt It thusrotates the spindle l4 about its longitudinal axis.

One end of the spindle l4 carries a face plate ll, which is similar. tothe face plate of a lathe, and this face plate, in turn, carries anadapter l8, which, in turn, carries removable bushings IS. The bodypart2 of a punch element is removably mounted axially in the adapter l8,so that the longitudinal axis E-E of the punch element is coincidentwith the axis of rotation of the spindle I4, in the same manner that arod to be turned is mounted and removably held in the chuck or collet ofa turning lathe. Standard 9 has a pair of parallel, rearwardly extendingarms 28 (see Figs. 4 and 6) which slidingly mount a platform 29 disposedabove the arms 28 and which extends forwardly over the table 10. Thismounting is similar to that commonly employed on machine tools, and hasV-shaped ways or grooves in which are slidingly mounted V- shaped edgesof platform 29. A lug 30 depends from platform 29 between arms 28, and aforwardly and rearwardly extending screw 3 I, which is parallel to thev-shaped ways, is threaded through the lug 30 and rotatably supported onstandard 9. A hand wheel 2| fixed on the forward end of screw 3| enablesone to rotate the screw in both directions and move the platformforwardly and rearwardly, which is cross wise of the direction of travelof table It]. On platform 29 is fixedly mounted a pedestal 20.

On the pedestal is mounted a supplemental moving table 22 which is setat an acute angle to the longitudinal axis of the spindle M or to thelength of the table [0, such as at the desired angle of divergence ofthe surface of the tapered part 4 of the punch element from the axis EE.This angle is preferably made about 20 but the angle may be varied asdesired. This moving table 22 is mounted on opposed V-grooves 32 ofpedestal 20 to move lengthwise of itself on the pedestal 20 by amechanism including a screw 23 rotatably mounted on table 22 andthreaded through a lug on the rear end of pedestal 20. The screw 23 isoperated by a hand wheel 24, in the same manner that the tool holder ofa lathe is mounted for movement across the table of a lathe. The movingtable 22 carries an arm 25 which extends toward the axis of rotation ofthe spindle I4, extended.

Mounted on the free end of the arm 25 is a suitable motor 26 with adepending spindle 2i driven thereby. This spindle 21 carries at itslower end the grinding wheel 6, shown diagrammatically on a large scalein Fig. 3. With the spindle 14 operating, say at a speed of about R. P.M. in a clockwise direction, and the grinding wheel 6 operating, say atabout 55,000 R. P. M., the grinding wheel 6 may be relatively shiftedlengthwise and slowly along the side of the piercing end 3 of the punchelement, at first along the axis GG from the position A to the position0. This relative movement in the illustrated embodiment is caused byoperation of hand wheel l0a or l2 to shift the head stock and punchelement past the grinding wheel and then with the head stock ll stoppedagainst further longitudinal movement in a direction along the table [0,which may be determined by a suitable, adjustable stop, the hand wheel24 may be operated to shift the grinding wheel 6 along a divergent pathrepresented by the line F-F, during which the grinding wheel 6 movesfrom position C through-position D beyond the end of the tapered part 4.With such an arrangement the convex, arcuate fillet 5 will have a radiusof curvature in transverse cross section corresponding to the radius ofthe grinding wheel 6. It provides a gradual transition between thecylindrical part of the piercing end 3 and the smaller end. of thetapered part 4. Because of the much greater speed of rotation of thegrinding wheel 6 about its axis, than the relatively slower speed ofrotation of the punch element, the ground grain on the side of the punchelement will be largely lengthwise of the piercing end of the punchelement.

Heretofore where the ground grain has run peripherally of the piercingend, such transverse grain has acted somewhat as a file and tended topick up small pieces of stock out from the blank being pierced, and tobind in the blank and female die. This causes an unsatisfactory aperturein the blank that is pierced, and it causes an undue wear on thepiercing end of the punch. The transversely ground grain also weakensthe piercing end so that it is more apt to fracture along such grainthan when the ground grain runs lengthwise.

It is believed that the operation of the device, and the manner ofgrinding, will be clear from the foregoing description. It will beunderstood that various changes in the details, materials andarrangements of parts, which have been herein described and illustratedin order to explain the nature of the invention, may be made by thoseskilled inthe art within the principle andscope of the invention, asexpressed in the appended claims.

I claim:

1. The method of grinding the punching stem and adjoining taperedportion of a punch element of a punch and die unit to form, on theperipheral wall of said stem, a ground grain running in directionsapproximately parallel to the axis of said stem, which comprisesmounting said element for rotation on the axis of said stem, mounting agrinding wheel with its axis of rotation crosswise of and ofiset fromsaid stem axis of rotation with its periphery engaging said element,causing relative movement of said grinding Wheel, while it is rotatingon its axis, bodily in a direction parallel to said stem axis, with theperiphery of the wheel in contact with said stem and at the contact zonemoving in a direction lengthwise of the stem, until said wheel reachessaid tapered portion, and then parallel to and in contact with saidtapered section along that section and rotating said grinding wheel atnot less than about 30 times the speed of rotation of said element.

2. A punch element for a punch and die unit of the type having a bodypart, a piercing end of reduced and circular cross section, and anintermediate tapered part connecting said body part and piercing end,said connection to said end being through a concave, arcuate surface,said element having a ground grain on the side face of its piercing endrunning in a direction approximately parallel to the longitudinal axisof said end from the end face of the piercing end to the intermediatetapered part, and then lengthwise along the concave surface.

3. The method of grinding the piercing end of a punching element of apunch and die unit to form on the side of said end, a ground grainrunning in directions approximately lengthwise of said element, whichcomprises mounting said element for rotation about the longitudinal axisof said end, mounting a grinding wheel for rotation about an axiscrosswise of and offset from said piercing end axis, with its peripheryengaging the element rotating said element about said longitudinal axisat a selected speed, rotating said wheel about its said axis at a speedin excess of ten times greater than said selected speed, bringing saidrotating wheel into contact with the side of said end, and then causingrelative movement between said rotating wheel and said element in adirection lengthwise of said rotating end.

4. The method of grinding the piercing end of a punching element ofcooperative punch and die parts to form on the side of said end a groundgrain running in directions approximately lengthof at least about thirtytimes greater than said selected speed, bringing said rotating wheelinto contact with the side of said end, then causing relative movementbetween said rotating wheel and said element in a direction'lengthwiseof said rotating end, for a substantial distance while maintaininggrinding contact of said wheel and element, and then progressively alonglengthwise said element but diverging progressively from saidlongitudinal axis of said end, while maintaining grinding contactbetween said wheel and element.

5. A piercing punch element of a punch and die unit for punching a discfrom a sheet blank, which comprises a metal body having at one end acylindrical punching stem, a larger diameter shank portion at the otherend by which said body can be mounted for endwise reciprocation, and anintermediate, tapered, frustoconical portion connecting said shankportion and said punching stem, said tapered portion merging into saidpunching stem through a concave, arcuate surface, the side surface ofsaid punching stem and of said arcuate surface having a ground surface,with the ground grain of said surface extending in a direction generallylengthwise of said body.

6. A tool comprising a body portion, a convergingly tapered portion onone end of the body portion, and a punching end portion of uniform crosssectional area along its length, forming an extension of the smaller endof said tapered portion, said end portion and said tapered portionjoining in a concave curve, said punching end portion having a groundperipheral surface with the ground grain of that surface running in adirection lengthwise of said punching end and tapered portions and upthe smaller end of the tapered portion.

JOHN F. KOPCZYNSKI.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 97,664 Marsh Dec. 7, 1869 744,340Heald Nov. 17, 1903 800,443 Horton Sept. 26, 1905 1,273,016 Ward July16, 1918 1,377,481 Hodgson May 10, 1921 1,511,842 Schmidt Oct. 16, 19241,667,231 Wood Apr. 24, 1928 1,864,584 Cowdery June 28, 1932 1,968,550Barnes July 31, 1934 1,974,365 Oliver Sept. 18, 1934 2,115,908 Fox May3, 1938 2,318,837 Connor May 11, 1943 2,356,272 Reynolds Aug. 22, 19442,373,459 Colwell Apr. 10, 1945 2,425,543 Landgraf Aug. 12, 1947 FOREIGNPATENTS Number Country Date 110,869 Great Britain Nov. 8, 1917

